Switching device



March so, '1937. p. E. BUCH ET AL 2,075,499

SWITCHING DEVICE Filed Jam 11, 1956 9 l8 F/G.3 I725 '24 2/3/ 23 22.273029 l/ I/ ll/ R EBUCH AAflAA/SEN A T TORNE' V Patented Mar; 30, 1937-UNITED STATES PATENT. OFFICE swrrcnmc DEVICE Application January 111936, Serial No. 58,652

1 Claim.

This invention relates to electromagnetically operated switching devicesin which contacts are operated by the movement of an armature inresponse to the energization of a magnet.

In swtiching devices of this type and in particular those used incertain telephone circuits, for example, where the motor magnet isenergized by an alternating current source, the core of the magnet, asis well known, isfltted with a copper plate which is provided tomaintain the magnet .energized during the reverse cycle of the current.In such magnets, however, it has been found that even the accuratedimensioning of such a plate with respect to the frequency used did notprevent chattering of the armature, and

that of the contacts actuatedthereby, and that this condition was thecause of objectionable noise or clicks generated inthe telephone talkingcircuit in which these relay contacts form a part.

The object of the invention is to provide a which is free of suchobjections.

In accordance with this invention, an electrospect to the energizingforce of the magnet on its armature.

Other novel features and advantages of the invention will appear fromthe following description and by the claim appended thereto, reference40 being had to the accompanying drawing, in which:

Fig. 1 is a front view of a magnet embodying the toggle mechanism of theinvention;

Fig. 2 is a side view thereof;

Fig. 3 is an enlarged top view showing the 45 magnet armature in itsretracted position;

Fig. 4 is another enlarged top view showing the magnet armature in itsoperated position;

Fig. 5 is a front view of a magnet showing a modification of theinvention, the magnet arma- 50 ture being shown in its retractedposition; and

Fig. 6 is a partial view of the modified magnet showing the armature inits operated position.

The alternating current magnet vto which the invention is particularlywell adapted for use 55 generally consists of a core 8 fitted at bothends switching device of the type above referred to with spoolheads l0and H and awinding l2. The core 9 extends beyond the spoolheads I0 and Hand is formed at its rear end with lateral projections for mounting anarmature IS in attractable relation with the prongs Pi and P2 formed atthe other end of the core, as shown in Figs. 3 and 4, the armature l3being attached to the rear end of core 9 by two similar ribbon springsl5 shown in Figs, 1 and 2 which permit the pivotal v movement of thearmature at this point. A cop- 10 per plate i6 is secured on spoolhead Hat the front end of the magnet and engages the prongs PI and P2 of thecore 9, the copper plate l6 being provided for holding the relayenergized during the reverse or negative cycle of .the current and 15on' this plate are mounted a number of screws, such as H, bearing on thecamming portions of springs, such as 20, secured to the arms of armature13 for returning this armature to its retracted position upon eachdeenergization of the magnet.

0n the copper plate i6 is secured, as by rivets 2| and 22, anangle-shaped bracket 23 having an upright extending lug portion 24provided for receiving a screw 25 which is axially movable therein bythe turning movement of nut l8, the screw 25 being held against turningmovement upon the turning of nut 18 by an arm Xi extending against thevertical portion of bracket 23, as shown in Figs. 2 and 3. Bracket 23 isformed with a portion 26 provided for mounting, as on a knife-edgepivot, a link member 21, having a slot 26 shown in Fig. 1 for engagingthe constricted portion of a nut 29 threadedly engaging a screw 30carried by armature 13, the link member 21 being held against thebracket portion 26 by a spring 3| having one of its ends hooked to thescrew 25 andits other end to the link 21, as shown in Figs. 1, 3 and 4,the line of maximum tension of spring 3i occurring where thelongitudinal axis of the link 21 forms a straight line with respect tothe attaching point of spring 3| on the screw 25, its pivotal point onthe bracket portion 26 and its attaching point with this link, and anydeviation of link 21 from such a line will cause the spring 3| to movethe armature I 3 either toward the core 9 of the magnet or awaytherefrom, as the case may be, for a purpose that will be hereinafterdescribed in detail.

The nut screw 29 may be moved on the screw 30 in position wherein thelink 21 will be moved to impart to the armature IS the desired pressuretoward the core in relation to the adjustment of the screw l1 bearing onthe camming portion of retractile spring 20.

In the modification of the invention shown in Figs. and 6, an arm 40 issecured on the ends of cores 4| and 42 by screws 43 and 44, the core 4|at this end being provided with a lug 45 for securing one end of aribbon spring 46 which serves as a pivot for the armature 41.

The arm 40 is provided at its free end with a lug 48 laterally extendingtherefrom for mounting a screw 49, the end of the screw having a conicalrecess for receiving the pointed end of a compression spring 50, and theother end of this spring engages a similar recess in the end of armature41, the line of maximum tension of spring 50 occurring when the pivotalpoint of armature 41, the axis of screw 49, and the engaging point ofspring 50 with the armature 41 are in straight line relation and anydeviation of the armature from such a line will cause the spring 5|] toforce this armature either toward the end of core 42 or toward the screw5| which limits the movement of armature 41 away from the core 42, thescrew 5| being adjustably mounted on arm 52 which is, in turn, securedto the core 4|.

In a typical example of operation of the device shown in Figs. 1, 2, 3and 4, the energization of the magnet and the consequent attraction ofarmature l3 from the position shown in Fig. 3 is efiective to move thelink 21 for tensioning the spring 3| to a maximum which occurs when thelink 21 forms a straight line with respect to its attaching points withthe screw 25, its pivot and its connecting point with the other end ofspring 3|. However, upon the continued movement of the armature and,therefore, the passing of link 21 beyond such a line, the link 21 ismoved in the position shown in Fig. 4 with the armature l3 engaging theprongs PI and P2 of the magnet, the tension of spring 3| being thuseffective to assist the magnetic flux as afforded by the copper plate IB in holdingthe armature in its operated position during the reverse ornegative cycle of the current and thereby preventing chattering of thearmature and that of the contacts actuated thereby under the tension ofthe retractile spring 20 which is adjusted to overcome the tension ofspring 3| uponthe complete deenergization of the relay. The change froma positive to a negative force on the armature can be adjusted to besuflicient to overlap the margin of pull which exists between the peakand the minimum values of flux produced by the alternating current sothat the relay once operated will remain so until the current appliedhas been appreciably reduced.

In an example of operation of the modification shown in Figs. 5 and 6,the compression spring 50 normally holds the armature in its retractedposition, as shown in Fig. 5, and in engaged relation with theadjustable screw 5|. Upon the movement of armature 41 when electromagnetI2 is energized, the spring 50 is compressed up to a point where thearmature is in line with respect to its pivotal point and the axis ofscrew 49. The

passing of armature 41 beyond such a line in en-.

gaged relation with the ends of the cores 4| and 42, the tension ofspring 50 as adjusted by the screw 49 is effective to assist themagnetic flux as afiorded by the copper plate IE to hold the armature 41in engaged relation with the core during the reverse or negative cycleof the current, thus preventing the chattering of the armature 41 andthe contact actuated thereby against the tension of retractile spring 60which is adjusted by the turning movement of nut 6| on screw 62 carriedby the magnet armature.

From the foregoing, it is apparent that we have provided a relay, theperformance of which is stabilized and certain of its operatingcharacteristics modified by an auxiliary spring. This relay thusprovides for a decrease in the holding current value as compared to theoperating current value; for slower operating or slower releasingwithout employing non-commercial contact spring adjustments; forincreased contact pressures. Also, when used in direct current relayswhich are normally held operated over considerable periods of time, theauxiliary spring by serving to reduce the holding force required on thearmature permits of the use of an auxiliary contact to insert resistancein series with the winding after the relay has been operated, therebyreducing current drain, or, in relays having heavy spring pile-ups theauxiliary spring can be employed to partially balance the build-up forceof the contact spring pile-up which develops as the relay armature isoperated and thus, without lessening contact pressures, permit economiesin winding design or decrease in the value of the required holding aswell as operating current, andin slow operate and release relays, theauxiliary spring by balancing part of the restoring force of the contactsprings may permit larger numbers of springs on a relay for a given slowcharacteristic or of increasing the time of release or operation.

It is to be understood that the auxiliary spring may be used to eitherpass from one side to the other of its line of. unstable equilibrium, tomove from one side only to its approximate line of equilibrium, or tomove from its line of equilibrium to one side of this line, and that anyof such arrangements fall within the scope of the invention.

What is claimed is:

In a switching device for use in a circuit energized by an alternatingcurrent source, a magnet having a core, a copper plate mounted at oneend of said core, an armature for said magnet, a toggle mechanismoperatively connected to said armature for assisting the magnetic fluxfurnished by said copper plate upon the reverse cycle of the current forholding the armature against said core, a retractile spring for saidarmature, and contact members operated by said armature.

PETER E. BUCH. ARNOLD A. HANSEN.

